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Search: id:A147627
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| A147627 |
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Numbers n = concat(a,b) such that bigomega(n) = bigomega(a) * bigomega(b), where bigomega = A001222. |
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+0
4
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| 23, 26, 28, 34, 37, 39, 53, 62, 65, 73, 74, 78, 93, 95, 104, 113, 119, 125, 134, 137, 138, 142, 143, 145, 155, 156, 173, 182, 193, 194, 197, 207, 211, 212, 213, 214, 215, 217, 221, 223, 226, 229, 230, 233, 235, 238, 241, 242, 244, 245, 249, 253, 260, 262, 265
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Concat(a,b) means decimal concatenation of a and b, i.e. a*10^[log[10](b)+1] + b, since we do not allow leading zeros in b.
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EXAMPLE
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a(4)=34 is in the sequence since bigomega(34) = 2 = 1*2 = bigomega(3)*bigomega(4).
206 is not in this sequence although bigomega(206) = 2 = 1*2 = bigomega(2)*bigomega(06), we do not allow leading zeros in the second part b.
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PROGRAM
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(PARI) is_A147627(n)={ local(p=1, o=biomega(n)); while( n>p*=10, n%p*10<p & next; o == biomega( n\p )* biomega( n%p ) & return(1))}
for( n=1, 999, is_A147627(n) & print1(n", "))
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CROSSREFS
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Cf. A001222, A147616 (analogue for sigma), A147619 (analogue for eulerphi), A147624 (analogue for omega).
Sequence in context: A112073 A050864 A111452 this_sequence A025059 A114963 A160774
Adjacent sequences: A147624 A147625 A147626 this_sequence A147628 A147629 A147630
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KEYWORD
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base,easy,nonn
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AUTHOR
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M. F. Hasler (MHasler(AT)univ-ag.fr), Nov 08 2008
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